[COLO-Frame,v19,17/22] COLO: Don't do failover while loading VM's state

Commit Message

Zhanghailiang Sept. 1, 2016, 3:24 a.m. UTC

We should not do failover work while the main thread is loading
VM's state. Otherwise it will destroy the consistent of VM's memory and
device state.

Here we add a new failover status 'RELAUNCH' which means we should
relaunch the process of failover.

Signed-off-by: zhanghailiang <[e-mail]>
Signed-off-by: Li Zhijian <[e-mail]>
Reviewed-by: Dr. David Alan Gilbert <[e-mail]>
---
v19:
- fix title
v14:
- Move the place of 'vmstate_loading = false;'.
v13:
- Add Reviewed-by tag
---
 include/migration/failover.h |  2 ++
 migration/colo.c             | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

Patch

diff --git a/include/migration/failover.h b/include/migration/failover.h
index c4bd81e..99b0d58 100644
--- a/include/migration/failover.h
+++ b/include/migration/failover.h
@@ -20,6 +20,8 @@  typedef enum COLOFailoverStatus {
     FAILOVER_STATUS_REQUEST = 1, /* Request but not handled */
     FAILOVER_STATUS_HANDLING = 2, /* In the process of handling failover */
     FAILOVER_STATUS_COMPLETED = 3, /* Finish the failover process */
+    /* Optional, Relaunch the failover process, again 'NONE' -> 'COMPLETED' */
+    FAILOVER_STATUS_RELAUNCH = 4,
 } COLOFailoverStatus;
 
 void failover_init_state(void);
diff --git a/migration/colo.c b/migration/colo.c
index fc89438..69d1948 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -20,6 +20,8 @@ 
 #include "qapi/error.h"
 #include "migration/failover.h"
 
+static bool vmstate_loading;
+
 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
 
 bool colo_supported(void)
@@ -51,6 +53,19 @@  static void secondary_vm_do_failover(void)
     int old_state;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
+    /* Can not do failover during the process of VM's loading VMstate, Or
+     * it will break the secondary VM.
+     */
+    if (vmstate_loading) {
+        old_state = failover_set_state(FAILOVER_STATUS_HANDLING,
+                                       FAILOVER_STATUS_RELAUNCH);
+        if (old_state != FAILOVER_STATUS_HANDLING) {
+            error_report("Unknown error while do failover for secondary VM,"
+                         "old_state: %d", old_state);
+        }
+        return;
+    }
+
     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
                       MIGRATION_STATUS_COMPLETED);
 
@@ -532,13 +547,22 @@  void *colo_process_incoming_thread(void *opaque)
 
         qemu_mutex_lock_iothread();
         qemu_system_reset(VMRESET_SILENT);
+        vmstate_loading = true;
         if (qemu_loadvm_state(fb) < 0) {
             error_report("COLO: loadvm failed");
             qemu_mutex_unlock_iothread();
             goto out;
         }
+
+        vmstate_loading = false;
         qemu_mutex_unlock_iothread();
 
+        if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
+            failover_set_state(FAILOVER_STATUS_RELAUNCH, FAILOVER_STATUS_NONE);
+            failover_request_active(NULL);
+            goto out;
+        }
+
         colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
                      &local_err);
         if (local_err) {
@@ -547,6 +571,7 @@  void *colo_process_incoming_thread(void *opaque)
     }
 
 out:
+    vmstate_loading = false;
     /* Throw the unreported error message after exited from loop */
     if (local_err) {
         error_report_err(local_err);